In a conventional bonding structures described in JP-A-8-152374, a bonding structure using glue between an annular concavity formed on a first body and an annular convexity formed on a second body is applied to a pressure sensor. The pressure sensor accommodates a sensor element in the first body. The sensor element is connected with a lead frame by gold wires or the like to transmit signals to outer devices such as ECU. A material used for the first body has to be heat-resistant so that the first body is durable for wire-bonding works. The first body is made of polyphenylene sulfide (hereinafter referred to simply as “PPS”) or the like. The second body is made of polybutylene terephthalate (hereinafter referred to simply as “PBT”) or the like. The concavity formed at the first body and the convexity formed on the second body are bonded with epoxy resin glue.
However, when the bonded first body and the second body are utilized under actual utilizing temperature condition, a peeling arises at the bonding structure due to difference of each coefficient of linier expansion of resin materials used for the first body, the glue, and the second body. Thus, a leak path is formed at the bonding structure. Pressure around the sensor element leaks, and becomes unstable. Thus reliability of the pressure sensor decreases.